Means for automatically controlling the tension of a continuously advancing element



1969 F. H. FREIMAN MEANS FOR AUTOMATICALLY CONTROLLING THE TENSION OF A CONTINUOUSLY ADVANCING ELEMENT Filed Jan. 5. 1967 United States Patent 3,486,713 MEANS FOR AUTOMATICALLY CONTROLLING THE TENSION OF A CONTINUOUSLY ADVANC- ING ELEMENT Freddy Herman Freiman, 58 Rue de Londres 75, Paris, Seine, France Filed Jan. 3, 1967, Ser. No. 606,883 Claims priority, application France, Jan. 7, 1966,

,144 Int. Cl. B6511 59/14; B65b 59/18 US. Cl. 242-155 11 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a device which allows for controlling simply, automatically and in a positive manner the unwinding tension of a continuously advanc ing Wire or band, and for maintaining the tension thereof at a specific value and Within very narrow differential limits.

The present invention is applicable generally to all those instances which involve the necessity of assuring a constant unwinding tension and, in view of the small tolerances which it renders possible, it is of particular interest to those applications which require a uniform tension between several wires or hands.

Mentioned herein, and by way of example for such applications, are the feeding devices of machines for making two, three or four stranded telephone wires which must keep standards of maximum unbalance. The more reduced the tensional differences between the two, three or four stranded Wires are, the smaller will be the finally achieved unbalance.

A device such as that proposed by the present invention is characterized particularly in that it comprises a resistance inducing element which allows a wire to unwind under the action of a pulling force and in opposition to a braking force, as well as an adjusting element which is controlled by said pulling force and is provided for producing, in response to the variations thereof, variations in the opposite direction in said braking force.

In accordance with a particular embodiment of this device, the resistance inducing element is a pulley which is set into motion by the wire to be unwound and is rigidly afiixed to a band brake.

The regulating element, on the other hand, may be provided in the form of a horizontally mounted slidable pulley block and maintained in balance under the opposing action of a predetermined weight and by two strands of a wire which is under tension, and the sliding displacements of the pulley which are brought about by the variations in the tension being exerted on the wire have the effect of displacing a counterweight on a control lever associated with the band brake.

Further objects, features and advantages of the present invention will become obvious from the following description when taken in connection with the accompanying drawing which schematically shows, by way of example, one embodiment of the present invention.

FIG. 1 shows the embodiment in schematic form; and

FIG. 2 shows a detail thereof in an enlarged scale.

Referring now to FIG. 1 of the drawing, reference 3,486,713 Patented Dec. 30, 1969 numeral 1 designates therein a wire which may be pulled continuously as at 2 by any desired device (not shown) and which originates at 3 from any desired element (also not shown), such as a drum, coil, ball, or the like. It is to be understood that the aforementioned element is actuated and provided in such a manner that the unwinding tension at 3 will not exceed a given constant tension which is desired to be obtained at 2.

The wire 1 passes continuously and successively over three pulleys 4, 5 and 6. It will be noted from the drawing that the strands 22, 23 travelling from the pulley 4 to the pulley 5 and from there to the pulley 6 are travelling in horizontal planes. The axles of the pulleys 4 and 6 are positioned in a stationary position. The axle of the pulley 5, on the other hand, is slidably mounted on a carriage 7 on a horizontal shaft 8. A light flexible wire 9 travelling over a pulley 10 having a stationary axle is loaded by a weight 11. The weight is freely movable, without friction, in a cylinder or tube 12 while the wire 9 is l-ayed about the pulley 10 by means of the horizontal strand 13 thereof.

In contrast thereto, the pulley 4 is integral with a disk 14, and supported on the latter is an inextensible brake band 15 which is connected with one of the extremities thereof to a fixed point 16 while the other extremity thereof is secured at 17 to a horizontal lever or rod 18 which is oscillatable around a pivot 19.

The rod of the lever 18 is provided with a stabilizing counterweight 20 which may be fixed in any convenient manner such as 'by a manual clasp adjacent to one side of the pivot 19. A second counterweight 21 which is adjustably mounted on the opposite side of the pivot 19 is adapted to glide therealong in a manner such as to follow the movements of the carriage 7 carrying the pulley 5. The connection between the adjustable counterweight 21 and the carriage 7 may be of any known type which will allow that these two elements may be jointly displaced without hindering the angular displacements of the lever 18. Thus, as shown in FIGS. 1 and 2, counterweight 21 is suspended from lever 18 by means of a hanger-rod 21A having a tray 21B and a lower extremity 21C which engages into socket element 7A of carriage 7. Counterweight 21 is composed of several units, which may vary in number to adjust the total weight acting on lever 18 through red 21A. Actually, these displacements are practically negligible because of the inextensibility of the brake band 15.

In order to reduce friction to a minimum, the sliding elements 7 and 21 may suitably be caused to glide by means of ball sockets, and thereby the weight of the carriage 7 and as well as that of the pulley 5 may be reduced as much as possible.

It will also be advantageous to assure the most efficient operation of this device that the rolling friction coefficient of the pulleys 4, 5, 6 and 10 be as low as possible.

Notwithstanding frictional phenomena as well as inertias and rigidity of the wire or band 1, the tension on each of the strands 22, 23 is equal to half the tension on the strand 13 as long as the pulley 5 is in balance under the action of these tensions and this can be attained as long as the carriage 7 glides freely without striking against one of the stops 24 and 25 which are disposed on the shaft 8. Thus, if it is desired to obtain at 2 a constant tension T, it is sufficient to give to the weight 11 the double of that value or 2T and to maintain the pulley 5 in balance under the action of the tensions exerted by the strands 13, 22 and 23 during the unwinding of the wire 1.

The device described hereinabove renders it possible to realize this balance automatically. As a matter of fact, the tension to be exerted for the purpose of unwinding the wire 1 is a function particularly of the braking power which is exerted by the band 15 on the disk 14 with the unit 4, 14 and 15 playing the role of the resistance inducting element. If this tension is greater than T, the movable carriage or unit 7 and counterweight 21 are displaced toward the left and the counterweight 21 will approach the pivot 19, which has the effect of slackening the brake band 15 and, consequently, reducing the unwinding tension of the wire 1. Conversely, if this tension falls below the value T, the carriage 7 is displaced toward the right, the counterweight 21 withdraws from the pivot 19 and the band 15 is tightened again. The counterweight lever or rod 18, together with the carriage 7 and the associated elements, thus constitutes a regulating element which is controlled by the tension exerted upon the wire 1 and has the effect of automatically correcting the differences in tension of this wire with respect to the specific or predetermined value T.

The sensitiveness of this regulator depends upon the frictional phenomena of the system and, in fact, allows for working with a very small tolerance. Moreover, these frictional phenomena are desirable to a certain extent since they have the effect of preventing a so-called pumping phenomenon. In order to reduce these phenomena, it is further possible to utilize a pneumatic damper means which is obtained by leaving free a laminar passage between the weight 11 and the tube 12 and which also has the purpose of preventing any inopportune balancing of the weight.

For the purpose of changing the tension at 2, it sufiices to modify the weight 11. As a matter of fact, the tension is greater than half of the weight 11 as a result of the rigidity of the wire 1, but the difference between these two values remains constant for the sum total and at the same speed. Additionally, this difference may be reduced by increasing the diameter of the pulleys 4, and 6.

The stationary counterweight 20 and the movable counterweight 21 may suitably be chosen as a function of the maximum tensions which are obtainable or which are to be obtained at 2, taking into account the frictional coefiicient of the band and the minimum tension of the wire at 3. It is possible, for example, to ensure the complete slackening of the band 15 before the counterweight 21 reaches the limiting or end position thereof at the left determined by the stop member 24, and to arrange the unit so as to obtain at 2 the desired tension when the tension at the inlet end indicated at 3 is at the minimum value thereof and prior to the movable counterweight 21 reaching the extent of its travel toward the right, this being determined by the stop member 25.

When several identical devices of the type described herein are assembled for feeding the machine with the same type of wire or band, the tension between the elements will remain the same at all times if the same weight 11 has been employed in each of the apparatus since the rigidity characteristics are the same for all of the devices.

It is to be understood that the present invention is in no way limited to the embodiments described and illustrated herein, but rather encompasses all of the variations and modifications as to detail thereof. For example, it is possible to mount the shaft of the pulley 5 in a slidable manner in two sockets or bushings instead of using the carriage 7 which is adapted to glide on the shaft 8. According to a still further embodiment of the present invention it is also contemplated that the carriage 7 may glide directly on the lever or rod 18.

The pulley 6 may be positioned below the strand 23 so that the pulling forces are directed downwardly rather than upwardly as shown in the drawing and the pulleys 4, 5 and 6 may be disposed symmetrically with respect to a horizontal axis.

A support-type slide block may be employed in lieu of the brake band 15, and the regulating unit, according to the present invention, may be connected to any resistance inducing device other than that which is exem- 4 plified by the elements 4, 14 and 15 shown in the drawing, for example, by means of friction rollers.

What is claimed is:

1. A device for the automatic tensioning of a continuously unwinding element, comprising a first rotatable annulus about which said element is guided, a brake for appling a clamping force to said annulus, a pivotal lever having a fulcrum and connected to said brake, said lever having adjustable counterweight means gliding therealong for controlling the clamping force of said brake, a second rotatable annulus about which said element is guided, said second annulus being movable relative to said first annulus, means traveling with said second annulus for moving said adjustable counterweight means along said lever, and dampening means for applying tension to the unwinding element about said second annulus.

2. A device for the automatic tensioning of a continuously unwinding element according to claim 1, further having stabilizing counterweight means on said lever remote from the adjustable counterweight means.

3. A device for the automatic tensioning of a continuously unwinding element according to claim 1, wherein the first annulus includes a disc mean, said brake means being in contact with said disc means.

4. A device for the automatic tensioning of a continuously unwinding element according to claim 2, where in the brake means is connected to said pivotal lever between the fulcrum point thereof and the stabilizing counterweight means.

5. A device for the automatic tensioning of a continuously unwinding element according to claim 1, wherein the second annulus is supported by a carriage means, said carriage means being movable on a horizontally disposed shaft means.

6. A device for the automatic tensioning of a continuously unwinding element according to claim 5, wherein stop means are provided at opposite extremities of said horizontal shaft means, said stop means adapted to control the movement of said carriage.

7. A device for the automatic tensioning of a continuously unwinding element according to claim 1, Where in a third annulus provided with a stationary axle is interposed between the dampening means and the second annulus.

8. A device for the automatic tensioning of a continuously unwinding element according to claim 1, wherein the unwinding element is led in substantially parallel planes to and away from the second annulus.

9. A device for the automatic tensioning of a continuously unwinding element according to claim 1, wherein the dampening means includes weight means, said weight means being arranged for friction-free reciprocation in a cylindrical means.

10. A device for the automatic tensioning of a continuously unwinding element comprising resistance inducing means in contact and moving with said unwinding element, braking means for resisting the movement vof said resistance inducing means for impeding the motion of said unwinding element, a pivotal lever having a fulcrum connected to said braking means and having adjustable counterweight means gliding therealong for controlling said resistance of said braking means, an annulus about which said element is guided, said annulus being movable relative to said resistance inducing means, said adjustable counterweight means connected to said annulus for movement therewith, and means for applying tension to the unwinding element about said annulus.

11. A device for the automatic tensioning of a continuously imwinding element according to claim 10, wherein said means for applying tension to said unwinding element include dampening means.

(References. on following page) 5 6 References Cited 3,113,746 12/1963 Steen 242-155 3,255,983 6/ 1966 Hays 242-155 UNITED STATES PATENTS 668,070 2/1901 Patten et a1. 242-155 2,252,419 8/1941 Slaughter 242-1562 X 5 us CL 3,080,133 3/1963 Muller 242155 242154 STANLEY N. GILREATH, Primary Examiner 

